Art of electrical precipitation of particles from fluid streams



(LVW. GIRVIN.

ART 0F ELECTRICAL PRECIPITATION 0F PARTICLES FROM FLUID STREAMS.

APPLICATION FILED FEB. 16. 191s.

1,378,224', L Patented May 17, 1921.

' v 2 SHEETS-SHEET l.'

A TTORNEY' C. W. GIRVIN. ART 0E ELECTRICAL PREC|PLTAT|0N 0F PARTICLESFROM FLUID STREAMS.

` APPLICATION FILED FEB. I6, 19I8. ,37,224

Patented SHEET 2- A TTOR/VEY UNITED PATENT" OFFICE- CEABLES w. Gravur',0F mLADELPHIA, PENNsYLvANrA.

Enron ELECTRICAL rEEcIPI'rATIoiI or PAETIcLEs Enom: FLUID STREAMS.

1'0 all whom z't may concern.'

Be it known that I, CHARLES W. GLRVIN, a citizen ofthe United States,residin in the city andcounty of Philadelphia, tate of Pennsylvania,have invented new and useful Improvements in the Art of ElectricalPrecipitation of Particles from Fluid Streams, of which the following isa speciication. l

This invention relates to the art of electrical precipitation ofparticles from iuid streams. i

Practice of this art involves the creation of an ionization field ,orfields in the iow path of a stream and collection of the deposits on thestream boundary or boundaries. The present invention is designed as oneembodiment in which the practice forming the basis of A'the patent'granted to me January 1, 1918, No. 1,252,104, may be convenientlycarried out, the disclosure of said patent providing the use of arotatable deposit-collecting electrode system, the ionization field orfields having permanentlylocated inactive portions accessible to the.

deposit-laden boundaries, the deposits being removed while in such fieldportions. As a result the deposit-laden surfaces are automaticallycleaned, enabling the apparatus to" operate continuously with little orno liability of the formation of dangerous disruptive discharge effects.v

In the present embodimentl various details of construction of anapparatus adaptedl forwide service conditions are presented,

these details being designed to meet various minor problems which mayarise in meeting varied conditions of service, these solutions h aving,through experiments, f'been .found to take care of the generalconditions which may be anticipated.

For instance, the use of annular fields tends to' complicate streamdistribution resulting' in decreased capacity for obvious reasons. Onefeature, therefore, is the means lwhereby stream distribution to thefields is rendered more uniform.

Another feature vis the approximate control of the stream iiow path asto practically eliminate movement of stream contents .through theinactive portion of the field Specication of Letters Patent.

Patented May 17, 1921.

l Application led February 16, 1918. .Serial No. 217,489.

Another feature is the substantial isolation ofthe inactive portion ofthe field to practically eliminatethe presence' of strain lines at thepoint of deposit-removal, thereby providing a space through whichdepos-- its may freely fall. This space may also bey utilized for thepassage of counter-currents which aid in causing lighter particles to becarried into the collection receptacle', a feature of advantage wherethe -deposits may tend to iioat, as for instance deposits of soot, etc.V I

To these and other ends, the nature of which will be readily understoodas the invention is hereinafter` disclosed, said invention consists inthe improved construction and combination of parts hereinafterl fullydescribed, illustrated in the accompanying drawings, and moreparticularly pointed out in the appended claims.v

In the accompanying drawings, in which similar reference charactersindicate similar parts in each of the views,-

Figure 1 is a diagrammatic sectional view taken vertically through aprecipitating apparatus according to the present embodi ment. v

Fig. 2 is a horizontal sectional view taken through the precipitatingchamber.

Fig. 3 'is a detail cross-sectional view i connected to the oppositeside of the source of electrical supply from that connected toi theactive electrode system.l To permit of securing the walls in position,support 10 is/ more or less spider-like (Fig. 2), the supportingdivision walls preferably lbeing wedge-shaped, as at 10n toward thedirection of stream advance. Support 10 may also carry additionalwedge-shaped rings 10", these wedge shaped portions being preferably,provided to more or less direct the stream contents as they enter theprecipi tating chamber. In the present embodiment the actlve electrodesystem iS .in the form of an upperspider 12 which includes annular rings12a or to the o posite side of the generator.

from which depend bars 18, the lower ends of the latter being secured inmembers 14 of more or less ring shape with a portion of the ringomitted, the lower vportion of the members also being preferablywedgeshaped in cross-section. i Bars 13 preferably extendvertically-although they may vary therefrom under certain conditions-andare of suitable cross-section, preferably angular with opposite edgesfacing the walls 11 when the electrode' is in position.

As shown in Fi 1, spider 1,2 is supported from a spider 15 y means ofinsulators 16, spider 15v being adjustably mounted on brackets, 17carried`by a casing 18 which surrounds the precipitation portion of theapparatus. The length of the bars 13 are such as to preferably llocatemembers 14 above the bottom plane of walls 11, thusL maintaining thedistance factor of the activeelectrode system from the support of of thecollecting system.

Spider 12 is connected to a suitable source offelectrical supply, suchfor instance as a high tension direct current generator, thecollecting/system being connected to grounId t will be unl erst'ood, ofcourse, ythat the source of electrical supply may be of any of thewell-known types, the apparatus operating with current of the pulsatingor continuous current, etc., types, as pointed out in the prior patent.

Support 10 i's mounted rotatably on a stationary su port 19 of properconfiguration, rolls or o her form of anti-friction means beingpreferably employed, support 10 being driven in suitable manner, as forinstance by a roller rotated bya shaft 20 operatively'connected to asource of powershown as a 'motor 21-through suitable connections such,for instance,.as a worm and worm-gear drive.

Casing 18 is carried by support 19 and inclos'es outer wall 11, theupper portion of the casing providing the entrance to the off-take Iyfor the cleaned fluid."

As will be understood, bars 13 cooperate with the op osing surfaces ofwalls 11 to reduce' elec ric fields, the strain line effect eingindicated somewhat in Fig. 3, being more o'r less individual to eachbar. Therefore, by proper spacingl of the bars the strain lines fromadjacent bars will `closely approach or overlap with the result that asubstantially continuous field throughout the spherel of influence ofthe bars, any apparently inactive' portions betweenbars not affectingthe generaloperation owing tothe wedge-shape' of members 14;, the lattertending to direct the entering stream awayfrom the bars andthereore intothe active fieldottiene 'rhg geref-ti ,tlen/igenenf-,-l there, ft'prvds:or ap uiraity of vertically exformed with active and inactive portions,the

latter being provided by omitting a predetermined number of bars 1,3--asindicated in Fig. 2, for instance-the absence lof such bars obviouslyleavingthe space practically free from strain lines and hence notadapted to the ionization action which takes place in the strain lineportion. This portion of`the field therefore becomes inactive forprecipitating purposes-and can be employed 4as the point where cleaning'of the -collecting electrodes can take place, the deposit-removaldevices being located in these portions.

As in the prior patented structure, cleaning is had by the use ofstationary structures which' act to scrape or brush the depositladenwalls,`the present disclosure employing a plurality of brushes 22carried by ele-v ments 23 having a general cross-sectional congurationsuch as shown in Fig. 4, thus projecting a curved face in the directionof advancing deposits and in advance of the brushes, forming apocket-like space in immediate advance of the brushes, the depositladenwall entering this space in reaching the brushes.

Element 23 and brushes 22 are preferably metallic, and since the brushesare in contact with the collecting walls or the deposit thereon, anystrain-line effect which might tend to enter into the pocket portion ofthe field, is taken up or shunted by the metallic connection between theelements and the grounded walls through the brushes. Consequently, thepocket-like spaces will be free from strain-line action Iand formpassages within which the removed deposits will readily move downwardlyinto the dust hopper 24 located therebelow, these deposits being'unaffected by the field action, these elements thus practicallyshielding the deposits during the removal period. As presentlypointedout, there is substantially no upwardly flowing fluid currents withinthese pocket-like spaces, and hence, under ordinary operatingconditions, the deposits will drop by gravity. Should thedeposits be ofa type whlch normally float, counter-currents can be set up in thesespaces as by the dellvery of suitable fiuid streams-air or cleanedgasz-into the upper end of the pocket-like spaces, nozzles 40 beingshown to indicate the direction of delivery. By the use of stream iuidwhich has been cleaned, the fluid introducedcan reenter the generalstream at the lower end of the spaces (ir/,through the side openingleading into the pocket, A .In. the present embodiment of the inventionthe direction of flow of the stream is tions of`t`he fields,therebyproviding more uniform action andthe ability to operate advantageouslywith maximum rates of stream fiow, I prefer to employ a distributionelement by means of which the stream is caused to be properlydistributed and delivered into the precipitating structure undersubstantially uniform conditions as to rate-of flow, distribution andpressure.

The general apparatus for producing these results, as disclosed,comprises a funnelshaped casing 25 extending downward from support 19,this casing forming the upper end of a receiving` chamber 26 for thestream contents, chamber 26 having a configuration which will cause thepoint of juncture of its walls with the lower end of casing 25 to act inthe nature of a constricted neck 27 between the chamber and the interiorof casing 25, chamber 26 operating somewhat as an expansion chamber forthe strean contents f entering through pipe 28 which forms the conduitfor the stream contents. As shown, the space within casing 25-with theexception of that occupied by the dust or deposit hopper 24-is providedwith a plurality of partitions 29- which sub-divide the space intocell-like passageways, open at opposite ends,

v the lower inlet ends having a smaller crosssectional area than theupper outlet ends.-

As will be understood, therefore, from Fig. 1, the stream contents aredelivered into chamber 26 in which more or 'less equal pressure is had,and then pass upwardly toward and into the contracted neck 27 whileunder such equal pressure conditions, the contracted upper end ofchamber 26 aiding in providing this result. Since partitions 29 extendinto this neck, distribution is equalized and the flow through thegradually-increasing area of the cells provides for proper delivery ofthe contents at the lower end of the precipitating chamber. To aid thisresult, I preferably discharge the stream contents from pipe 28 in adownward directionopposite the direction of fiow in chamber 26-andthereby break down vany tendency of the pressure of the entering streamcontents disturbing the desired equal pressure conditions at thecontracted neck. In addition, this arrangement permits the lower end ofchamber 26 to be formed as a pocket into which heavier particles maygravitate, the pockethaving a suitable closure, indicated conventionallyat 30, through which these deposits may be removed. Obviously, suchparticles may so gravitate at any point inthe upward travel of thestream, and the contracted lower end of the chamber will cause them topass into the pocket', thereby providing a preliminary treatment of thestream contents which-will aid in the'general operation.

Dust or deposit hopper or receptacle 24 is located below the inactiveportions of the field, as heretofore pointed out, and may be of anydesired shape. I prefer, however, to v employ a configuration 0f itsupper end such as will cause the hopper to serve in the nature of abaffle for the inactive field portions. I also prefer to incline theinner wall of the hopperv in such way as to tend to deflect the streamlcontents without forming any material dead pocket of the stream todisturb the stream flow. The hopper is provided with any suitable formof closure-indicated conventionally at 24afor removal of the lcollecteddeposits.

` As a guide in determining the comparative size of the upper end of thehopper when employed for baffle purposes, I would state that experimentshave shown that under general conditions and in an apparatus ofcomparatively large capacity, I have found that this area lneed notexceed .2(.7854D2) where .7854132 equals the total cross-sectional areaof thev precipitation chambers, D representing the diameter 0f theoutside precipitating wall, giving an approximate net cross-sectionalarea ofthe cleaner as .63D2- As an example of general size of apparatus,the following may be considered:

An apparatus designed to treat 50,000 cubic feet of gas per minute, withthe stream flow rate as 8 feet per second, would employ an apparatushaving the total net effective cross-sectional areay of 104 square feet,with the diameter 12.8 feet, these dimensions being approximate.

As will be understood from Fig. 2, any stream contents which would enterinto the inactive portions of the field, must traverse active field`portions and be subjected to the action thereof.

If desired, suitable packing may be employed to I4prevent leakage .ofgas stream contents from chamber 26 into the space external of outer-wall 11. Y

While I have herein shown and described a preferred embodiment of theinvention, it will be readily understood that changes and modificationstherein vmay be found necessary or desirable in meeting the .variousexigencies of use, Vand I desireI to be understood as reserving theright to make any and all such changes or modifications therein as maybe found desirable or essential in so far as the same 'may fall withinthe 55 n the deposit laden face.

invention,

'field activity, and means whereby deposits collected .on a face of oneof said systems will be removed from such face while free from suchactivity.

2. In apparatus of the character described and wherein opposingelectrode systems are movable relatively to each other and adapted toproduce an electric field or fields, means for removing deposits from adeposit-collecting face of one of said systems, said means including anelement operative to isolate a space of predetermined cross-sectionalarea free from field activity and within which. d posit removal may behad.

3. I n apparatus of the character described and wherein opposingelectrode systems are movable relatively to each other and adapted toproduce an electric field or fields, a rotatable wall forming part ofone of the systems and having a deposit-collecting face, and means forremoving the deposits from said face, said means including an elementoperative predetermined cross-sectional area free from field activity,said wall forming a space-defining wall.

4. Apparatus of the character of claim 3, characterized in that theelement operative to roduce the isolated space carries means or removingthe deposits, said means being located at the rear of the space, wherebythe deposits are free to travel in such space.

5. In apparatus of the character described and wherein opposingelectrode systems are movable relatively to each other and adapted toproduce an electric field or fields, an element within the' field andoperative t0 kisolate a space of the field free from field activity,said space being adjacent a deposit-laden face of one system, .and meansoperative on deposits of said face within said space for removing suchdeposits from 6. Apparatus as in claim 5 characterized in that'the meansextends in the direction of stream travel through the apparatus.

7. Apparatus as in claim 5 characterized in that the means extendssubstantially vertically.

8. Apparatus as in claim 5 characterized in that the space hasjitsdirection o f length cto isolate a space of extending vertically,whereby the removed deposits may gravitate from the space.

9. Apparatus asin claim 5 characterized in that the space has itsdirection of length corresponding to the direction of flow of the streambeing treated.

l0. Apparatus as in claim 5 having means for directing a fiuid pressurein the direction of length of the space.

11. Apparatus as in claim 10 characterized in that the direction. offluid pressure flow is counter to the direction of stream flow throughthe apparatus.

12. In apparatus of the character described, wherein opposing electrodesystems are adapted to produce an electric field operative forprecipitating purposes and` may.

13. Apparatus as in claim 12 having means operative within the chamberfor eliminating stream particles therefrom by gravitation. p

14;. In apparatus of the character described, wherein opposing electrodesystems are adapted to produce an electric field op.-

erative for precipitation purposes and wherein the flow path of thestream is confined within substantially concentric limits, a chamber inadvance of the field for receiving the stream contents to be treated,Said chamber having a contracted outlet and tending to control thestream distribution, and a cellular structure intermediate said outletand the field for substantially maintaining the stream distributionduring its passage to and within the zone of preclpitation activity.

15. In apparatus of the character described, wherein opposing electrodesystems:

are movable relatively to each other and adapted to produce an electricfeldopera-y tive for preclpitation purposes, and whereln' precipitateddeposits are removed from a deposit-laden face at a predetermined. pointof such field, means for introduclng a stream to such field, and adeposit-receiving chamber located in the stream owath and operative as adirection-control actor in the stream movement to the field.

16. In apparatus of the character described, wherein opposing electrodesystems are movable relatively to each other and adapted to produce anelectric field operativev for precipitatio1-\purposes, and wherement toindividual in precipitated deposits are removed from means in the flowpath of thev stream for controlling the direction of stream moveportionsof the eld. 17. Apparatus as in claim'l' characterized in that the'means includes a, distributing element operative to substantiallyequalize stream distribution to the field.

18. Apparatus as in claim 16 characterized in that the means includes aninstruoperative to limit stream delivery v mentality to active portionsof the iield, anda distribution element operative to substantiallyequalize vthe distribution of the delivered stream.

19. In apparatusY of the character described, wherein opposing electrodesystems are movable relatively to each other and adapted to produce anelectric iield having active and inactive portions operative orpredipitation purposes, and wherein precipitated deposits are removedfrom a deposit-laden face at a predeterminedl point in the inactiveportion of the iield, means for introducing a stream to such field fortreatment,- and means operative in the stream fiovv' path in advance ofthe field A for controlling the direction of streamy movement toindividual. portions of the field and active to limit stream delivery toactive portions of the field. i

20. In apparatus of the character described, wherein opposing electrodesystems are lmovable relatively to each other and adapted to roduce anelectric eld having active and inactive portions operative forprecipitation purposes, and wherein precipitated deposits are removedfrom a depositladen face at a predetermined point in the inactiveportion of the ield, and a depositreceiving chamber located in thestream iow path beneath a field inactive portion and operative to limitstream delivery to active portions of the iield.

21. In electrical precipitating apparatus,

opposingelectrode s duce an electric fiel system includingv spaced-apartfaces, tem including a plurality of spaced-apart bars extending inparallelism `and arranged in \a segmental series positioned vsubstantially 'concentric with the outer face of the stems adapted toproconcentrically arrange .collecting system and between adjacentcollecting faces of such system.

Signed thisflth dajylof Februar. 1918.

. CHAR ES W. GIR IN.

the deposit-collecting' the active discharge sys`

